1. Field of the Invention
The present invention relates to a water-based ink set for ink-jet recording capable of producing images that absorb infrared light, to an ink-jet recording method using the ink set, and to an ink-jet recording apparatus for implementing the method.
2. Description of the Related Art
As inks for producing code marks such as bar codes and OCR characters, infrared absorptive inks capable of producing visually unreadable code marks have been developed to improve security. As such infrared absorptive inks, for example, there were proposed inks in which a cyanine-based or naphthoquinone-based coloring agent is used and inks in which a coloring agent composed of a resin containing powder of tin-doped indium oxide (ITO) is used.
The above-mentioned infrared absorptive inks in which an organic-based coloring agent is used have a problem that the color tones of the inks cannot be controlled, because the inks have absorption in the visible range. Meanwhile, the infrared absorptive inks in which ITO powder is used have little absorption in the visible light range. ITO powder is an expensive material. In addition, generally, ITO powder is often used in inks containing an organic solvent and other similar inks and cannot be used in water-based inks and in ink-jet recording methods using the water-based inks. Moreover, in recent ink-jet recording methods, a printer is used which is provided with a replaceable ink cartridge containing an ink set composed of a plurality of different inks. In such a case, there is a demand that at least one of the inks constituting the ink set be an infrared absorptive ink having absorption in the infrared range to improve security of recorded objects.